Power Silicon MOSFETs, BJTs, IGBTs
Technical Lecture Session
GaN/Si Devices and Components
Active EMI filter, MOSFET, Synchronous rectifier, Linear operation
This work discusses the capability of linear, reverse operation of a power MOSFET. In conduction phase of a synchronous rectifier (SR), the MOSFET channel is fully turned on to minimize loss. The authors find another operating mode of a SR MOSFET: the drain voltage exhibits a linear relationship to gate voltage where the gate voltage level is around its threshold VTH but without activating the body diode. This linear relationship holds from DC to MHz range, so the reverse-operated MOSFET can be utilized to inject signal to the power circuit. An active rectifier bridge with EMI mitigation function is built with SR MOSFETs demonstrating an application of the proposed linear control technique. Measurement of the linear characteristics for different MOSFET samples is exhibited. The active bridge prototype is used to replace the diode bridge in a PFC converter. Experiment shows EMI reduction, filter size reduction as well as loss reduction.